In recent years, with copy machines or printers having improved in performance, copies of banknotes, securities, and the like copied with such copy machines or printers have frequently been misused. Against such a background, in order to inhibit forgery or such misuse of the copies, establishment of a technique of precisely determining authenticity of various types of paper documents (including, for example, passports, title certificates of various types, residence certificates, birth certificates, insurance certificates, guarantee certificates, confidential documents, and the like, in addition to the above described banknotes or securities) has long been awaited.